Stirring device for laboratory fermenters



May 21, 1957 A. B. HATCH 2,

STIRRING DEVICE FOR LABORATORY FERMENTERS Filed Oc t. 18, 1952 2 Sheets-Sheet l INVENTOR. ALDEN B. HATCH BY JOHN P. MURPHY ATTORNEY May 21, 1957 A. B. HATCH STIRRING DEVICE FOR LABORATORY FERMENTERS 2 Sheets-Sheet 2 Filed Oct. 18. 1952 FiG.3

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vFIGS INVENTOR. ALDEN B. HATCH BY JOHN P. MURPHY ATTORNEY United States Patent STIRRING DEVICE FOR LABORATORY FERMENTERS Alden Bruce Hatch, Fayetteville, N. Y., assignor to liristol Laboratories Inc., Syracuse, N. Y., a corporation of New York Application October 18, 1952, Serial No. 315,500

3 Claims. (Cl. 195-143) This invention relates to improvements in means for stirring fermenter liquids and, more particularly, to a coupled stirrer shaft for use in laboratory fermenters.

Laboratory fermenters of the prior art, such as those described and referred to by Brown and Peterson, Ind. Eng. Chem., 42(9), 1769 (1950) have not proven wholly satisfactory, primarily because all designs have required far too much manpower and time for putting into operation and for cleaning after operation.

The art of cultivating microorganisms such as, yeasts, Penicillium, Aspergillus, Streptomyces, etc. in small agitated and aerated fermenters where pure culture conditions are essential has been severely handicapped and rendered costly in the past because the top of the fermenters could not be hinged and opened like a simple hinged cover to enable cleaning for the reason that the agitator shaft is attached to the top through a stuffing box and steady bearing and must be removed along with the top to enable cleaning. I have now discovered a mechanism which overcomes this difliculty and because of its peculiar attributes unexpectedly simplifies many additional features of construction and operations to such a point that large numbers of fermenters can now be operated in a much shorter cycle time and with surprisingly less manpower requirements, auxiliary equipment and floor space.

In one form of the conventional art glass or metal fermenters with all services passing through the top cover are assembled, filled with ,medium' andplaced in large 6 x 6 x 12 foot autoclaves for sterilization. Following sterilization, they are cooled and then are moved individually into large constant temperature water baths. Air, agitator power, antifoam oil connections, steam lines, etc. are then connected and eventually the chambers can be inoculated and fermentation can be commenced. Because of the necessity for making numerous connections and the tendency for air to leak into the chambers during cooling and also because of the absence of steam in the sparger to keep it free of medium, many difficulties ensue, sparger lines become clogged and adequate aeration is impossible, contaminations creep in with unsterile air, etc. After the fermentation is completed, it then becomes necessary to disassemble such fermenters by lifting the top with its agitators and numerous connections clear of the chamber. All parts of the apparatus must be washed before the process can be repeated. The complete cycle of assembly,'sterilizing, connecting, fermenting and cleanugrequires a great deal of labor, fioor space provided with water, etc. and a large, costly autoclave.

In another form of the art, the fermenters are pressure vessels sterilized in situ with steam at to lbs., but the fermenter top with its agitator and other connections must be disassembled as in the former case for cleaning. Also, the fermenter must be very small since the agitator shaft can not be provided with a bottom hearing.

In still another variation of. the art, agitation is achieved by rotating magnets without a stuffing box, but a shaft and bottom bearing are still necessary and these must still be attached to the top of the fermenter and must be removed with the top for cleaning.

There is now discovered, according to the present invention, a coupling located in about the top third of the vertical impeller shaft in a laboratory fermenter having an inside diameter of less than thirty inches and having a removable top through which the upper portion of the impeller shaft is mounted perpendicularly and through which the shaft is connected to driving means.

In the drawing:

Figure 1 is an isometric view of one form of the fermenter embodying the invention, with the automatic magnetic coupling illustrated schematically.

Figure 2 is an isometric view of the magnetic coupling.

Figure 3 is a cross-sectional view of a pin-and-socket embodiment of the interlocking means located on the facing plates of the magnetic coupling.

Figure 4 is a cross-sectional view of one embodiment of the magnetic coupling means located on the facing plates of the magnetic coupling.

Figure 5 is an isometric view of one embodiment of the magnetic means on the coupling plates used in conjunction with the hinged alignment bar.

Figure 6 is an isometric view of the hinged alignment bar.

As shown in Figure I, there is provided in this fermenter 18 a chamber having a height of about two or more times its diameter. A cylindrical shape is preferred to simulate better the conditions in larger tanks and to facilitate fabrication. The vertical sides may be provided with a jacket 9 asmeans to control the interior temperature, said jacket being provided with means for circulating heating or cooling fluids or gases. The jacket preferably encircles the lower two-thirds of the side of the fermenter. At the bottom there is a drain 6 beneath a steady bearing 5 which supports the shaft 15 when it is uncoupled and maintains the shaft in alignment at all times. Approximately around the drain and steady bearing is the sparger 7. A sampling outlet valve may be provided at 8. Baflies such as 4 may be disposed on the interior wall of the fermenter. Impeller blades such as 3 may be attached to the shaft as desired. There is an outlet 1 for sparger air. Inlets for medium, inoculum, antifoam and the like may be provided, as by 2.

A magnetic adjustment bar 11 may be provided along the interior, vertical wall as means for holding the bottom portion of the uncoupled shaft in alignment before coupling. After coupling and the consequent slight vertical movement of the lower portion of the shaft, the alignment bar automatically drops down out of the way.

The cover 19 of the fermenter 18 is removable, and is hinged 17 for ease of handling. The cover is adapted to be held in a gas-tight closed position. There may be inserted through the cover a spark-plug 12 of the type used to indicate height of foam. A sight glass 13 may be inserted in the cover. The motor 14 for the impeller shaft may be located remote from the center of the cover. To increase the ease of removing the cover, the stirrer 29 is preferably run by a flexible power cable 30. The shaft 15 extends from the motor through the top in vertical fashion when the cover is closed; the shaft is provided with a gas-tight seal and steady bearing.

The construction may be glass-lined etc. but stainless steel is preferred. All inlets and outlets are protected from contamination in the usual manner as by steamtrapped valves. When closed the fermenter is gas-tight.

In a preferred embodiment of the coupling 10, use is made of the magnetic coupling device shown in Fig. 2. The two pieces of the shaft 15 bear heads 22 which are a few one-thousandths of an inch apart when the top of the fermenter is closed and the shafts are vertical. Magnets 20 and pins 21 and pin holes 23 in the heads,

r 3 when turned opposite one another, serve to hold the two heads together. As the top head is fixed and the bottom head is free, the attraction between the magnets is sufficient when the top is closed to automatically raise the bottom shaft and head for the necessary, small distance so that intimate contact is maintained. A magnet 26 in the side of head 22 attracts the alignment bar of Fig. 6. Rotation of the shaft during operation dislodges the optional magnetic alignment bar of Fig. 6, which then falls clear. This magnetic coupling may also be so constructed that the magnets serve as drive pins by virtue of the protrusion of one magnet from a head and the recession of the corresponding magnet in the other head.

Figure 6 shows an embodiment of the optional magnetic alignment arm attached to the inner side wall of the fermenter. In operation the hinge 24 is raised until the arm 27 is horizontal. The magnet 25 in the end of the arm then makes contact with a magnet 26 facing out from the side of the head on the lower portion of the impeller shaft as shown in Figures 2 and 5. This attraction serves to hold the lower shaft in exact alignment while the top of the fermenter is lowered. In automatic operation, the slight elevation of the lower shaft and head, when contact is made, or the rotation of the shaft during operation of the fermenter serves to break apart magnets 25 and 26. The alignment bar then falls free of its own weight upon hinge 24 until the arm is free and cleai and vertical 28. v

In all cases, the top portion of the coupling device is located near enough to the top of the vessel so that the coupler will clear the side of the fermenter when the top is opened, as by swinging it open upon hinge 17. When the top is hinged just outside the fermenter wall and the height of the fermenter, as is customary, is about twice its diameter, this requirement serves to locate even a very small coupler at a point no more than about onethird of the distance down the shaft from the top. An increase in the ratio of height to diameter or in the size of the coupler necessitates moving the coupler closer to the top.

In operation, the top is unbolted and swung open, most conveniently upon hinge 17, although it may be lifted off. This operation is facilitated by having inserted in said top only a small spark plug with attached wire and a small stirrer, preferably supplied with power through a flexible power cable. If desired the lower portion of the impeller shaft is then lifted out by hand without removing any bolts, screws or obstructing bearings. The entire apparatus can then be easily scrubbed out and cleaned. The impeller shaft is then replaced if removed.

When the magnetic coupler is to be used, the alignment bar is then raised to the horizontal position and thus holds the lower shaft in correct alignment. The top is then replaced and bolted down. A simple twist of the shaft motor serves to align the drive pins with their holes. The magnetic attraction between the two heads lifts the lower head until they are in perfect contact. This elevation releases the alignment bar, which falls to the side. The apparatus is then sterilized. This use of the alignment bar is convenient but not essential.

Sterilization is most easily elfected by flushing out with steam and then closing all valves and admitting steam under fifteen to twenty pounds gauge pressure for about fifteen minutes. Sterile air may then be passed in through the sparger and out the outlet underslight pressure to prevent clogging the sparger holes while sterile media and inoculum, etc., are introduced. The fermentation is then conducted under any desired conditions'of aeration, stirring and temperature etc. Samples may be withdrawn as desired.

At the end of the fermentation, all of the liquid and solids in the fermenter are removed through the drain valve in the bottom of the fermenter.

In the case of the magnetic coupler, the top is simply unbolted and removed and the cycle may be repeated.

The use of the coupling of the present invention enables laboratory fermentatiohs to be carried out with much less time and man-power spent in cleaning the fermenter and preparing it for the next run than is possible with other forms of this apparatus. The resultant de crease in cycle time makes possible more extensive studies of process improvements' In addition, requirements for floor space and equipment are minimized. No large, costly autoclave is required.

As will be readily apparent, both portions of the impeller shaft lie in the same straight line and all coupling devices are uniformly distributed about this line to avoid eccentricity, shimmy or sway.

An understanding o'ffthis invention may be obtained by reference to the examples above but these examples are illustrative only and are not the exclusive embodiment of this invention. It is further obvious that various changes may be made in details within the scope of my claims without departing from thespirit of my invention.

in vertical position insaid chamber; and a driven impeller shaft located within s aid chamber, said coupling means being located within said chamberan'd comprising top and bottom engageable plates, saidtop' plate being centrally affixed to the'lower cnd'bfs aid shaft and being in normal position theretopsaitl bottom plate being cen- 1 t'rally hflixed to thc' oppriend ofsaid driven shaftand being'in normal positioifthereto, said'top "plate being so located in said chamber that when said cover is opened said plate'does'notengage the sides of said chamber, said plates being provided on their opposing faces with magnetic means, said plates being adapted when said cover is in the closed position to engage each other magnetically in a fixed and registered position and with both impeller shafts being in axial. alignment, and interlocking means located on the opposing faces of said plates to prevent slippage thereof during high speed rotation of said impeller shafts and means of maintaining'said driven impeller shaft in vertical-position with its top plate in alignment for magnetic engagement with said bottom plate of said driven shaft.

2. Coupling means for a laboratory ferrnenter having a cylindrical chamber with a diameter of less than thirty inches, a hinged cover for closing said chamber, a driving impeller shaft extending centrally through said cover and having a portion above said cover which may be driven and having another portion centrally depending from said cover and being adapted to normally extend in vertical position inzsaid chamber, and a driven impeller shaft located within said chamber, said coupling means being located within said chamber, and comprising top and bottom cngageable platesQsaid top plate being centrally affixed to the lower end of said driving shaft and being in normal position thereto, said bottom plate being centrally affixed to the upper end of said driven shaft and being in normal position. thereto, said top plate being so located in said chamber that when said cover is opened said plate does not engage the sides of said chamber, said plates being provided on their opposing faces with magnets solocated that the north and south poles of the magnets of one plate are exactly opposite the south and north poles of the magnets of the other plate, said plates being adapted when said cover is in the closed position to engage each other in registered position with the magnets of one'plate engaging the magnets of said other v plate and with both impeller shafts being in axial alignhigh speed rotation of said impeller shafts and means of maintaining said driven impeller shaft in vertical position with its top plate in alignment for magnetic engagement With said bottom plate of said driven shaft.

3. Coupling means and alignment means for a laboratory fermenter having a cylindrical chamber With a diameter of less than thirty inches, a hinged cover for closing said chamber, a driving impeller shaft extending centrally through said cover and having a portion above said cover which may be driven and having another portion centrally depending from said cover and being adapted to normally extend in vertical position in said chamber, and a driven impeller shaft located within said chamber, said coupling means being located Within said chamber and comprising top and bottom engageable plates, said top plate being centrally afiixed to the lower end of said driving shaft and being in normal position thereto, said bottom plate being centrally afiixed to the upper end of said driven shaft and being in normal position thereto, said top plate being so located in said chamber that when said cover is opened said plate does not engage the sides of said chamber, said plates being provided on their opposing faces With magnetic means, said plates being adapted when said cover is in the closed position to engage each other magnetically in a fixed and registered position and With both impeller shafts being in axial alignment, and interlocking means located on the opposing faces of said plates to prevent slippage thereof during high speed rotation of said impeller shafts, said alignment means comprising a bar hingedly affixed to said fermenter to allow said bar to drop to a vertical position of its own Weight and having magnetic means thereon, said bar When in horizontal position being adapted to maintain magnetically the second mentioned impeller shaft in positive vertical and horizontal alignment until the magnetic alignment effect is broken by rotation during operation.

References Cited in the file of this patent UNITED STATES PATENTS Spears June 12, 1951 

1. COUPLING MEANS FOR A LABORATORY FERMENTER HAVING A CYLINDRICAL CHAMBER WITH A DIAMETER OF LESS THAN THIRTY INCHES, A HINGED COVER FOR CLOSING SAID CHAMBER, A DRIVING IMPELLER SHAFT EXTENDING CENTRALLY THROUGH SAID COVER AND HAVING A PORTION ABOVE SAID COVER WHICH MAY BE DRIVEN AND HAVING ANOTHER PORTION CENTRALLY DEPENDING FROM SAID COVER AND BEING ADAPTED TO NORMALLY EXTEND IN VERTICAL POSITION IN SAID CHAMBER, AND A DRIVEN IMPELLER SHAFT LOCATED WITHIN SAID CHAMBER, SAID COUPLING MEANS BEING LOCATED WITHIN SAID CHAMBER AND COMPRISING TOP AND BOTTOM ENGAGEABLE PLATES, SAID TOP PLATE BEING CENTRALLY AFFIXED TO THE LOWER END OF SAID DRIVING SHAFT AND BEING IN NORMAL POSITION THERETO, SAID BOTTOM PLATE BEING CENTRALLY AFFIXED TO THE UPPER END OF SAID DRIVEN SHAFT AND BEING IN NORMAL POSITION THERETO, SAID TOP PLATE BEING SO LOCATED IN SAID CHAMBER THAT WHEN SAID COVER IS OPENED SAID PLATE DOES NOT ENGAGE THE SIDES OF SAID CHAMBER, SAID PLATES BEING PROVIDED ON THEIR OPPOSING FACES WITH MAGNETIC MEANS, SAID PLATES BEING ADAPTED WHEN SAID COVER IS IN THE CLOSED POSITION TO ENGAGE EACH OTHER MAGNETICALLY IN A FIXED AND REGISTERED POSITION AND WITH BOTH IMPELLER SHAFTS BEING IN AXIAL ALIGNMENT, AND INTERLOCKING MEANS LOCATED ON THE OPPOSING FACES OF SAID PLATES TO PREVENT SILPPAGE THEREOF DURING HIGH SPEED ROTATION OF SAID IMPELLER SHAFTS AND MEANS OF MAINTAINING SAID DRIVEN IMPELLER SHAFT IN VERTICAL PORITON WITH ITS TOP PLATE IN ALIGNMENT FOR MAGNETIC ENGAGEMENT WITH SAID BOTTOM PLATE OF SAID DRIVEN SHAFT. 